This project seeks to develop an improved CASA (computer-aided sperm analysis) instrument for measurement of sperm motion characteristics. Hamilton Thorn Research currently markets its first generation product, the HTM Motility Analyzer. The proposed work intends to improve upon the existing system by: (1) incorporating stroboscopic illumination - to lessen position identification errors due to image blurring of rapidly moving sperm; (2) developing new software and optical hardware to help distinguish non-motile sperm from other particular matter in the sperm suspension; and (3) performing experiments that test the improvements provided by the new prototype system. These experiments will be performed on rabbit semen, and it is argued that initial adaptation to the rabbit is important for future applications in male reproductive toxicology.